IP Addressing Scheme (Topic 4)

Textbook:

Networking Basics, CCNA 1 Companion Guide

, Cisco Press Cisco Networking Academy Program,

CCNA 1 and 2, Companion Guide

, Cisco Press, Latest Edition CIM 2465 IP Addressing Scheme 1

IP Address Fundamentals

• Logical address • IPv4 (32 bits, usually in dotted-decimal, e.g. 192.168.123.1) • Must be unique inside a particular network CIM 2465 IP Addressing Scheme 2

Address Assignment (1)

• All hosts on the same LAN must use the same value for the first part of their IP addresses (length depends on size of the network) • IP addresses are assigned to network interfaces rather than to entire computers CIM 2465 IP Addressing Scheme 3

Address Assignment (2)

• ipconfig CIM 2465 IP Addressing Scheme 4

Address Assignment (3)

• 3 key rules – Devices on the same LAN must use IP addresses in the same group (IP network) – Devices on different LANs that are separated by at least one router must use IP addresses in different IP networks – IP addresses must be unique inside the same internetwork • Fig 9-13 CIM 2465 IP Addressing Scheme 5

• Three networks – All IP addresses that begin with 10 – All IP addresses that begin with 11 – All IP addresses that begin with 12 CIM 2465 IP Addressing Scheme 6

Network Classes (1)

• Unicast IP address – An IP address that can be assigned to a single interface • IPv4 defines 3 three classes of unicast IP addresses, determined by the value of the first octet of the address • An address includes two parts (no subnetting) – network part – host part

Range of values In first octet

1-126

Class

A

Length of Network Part

1 octet

Length of Host Part

3 octets 128-191 B 2 octets 2 octets 192-223 C 3 octets CIM 2465 IP Addressing Scheme 1 octet 7

• Fig 9-14

Network Classes (2)

• A unicast IP address determines its class and structure, specifically, the size of the network and host parts of the address • An IP network consists of all unicast IP addresses for which the network part’s value is the same CIM 2465 IP Addressing Scheme 8

• Fig 9-15

Network Classes (3)

IP Address 10.1.1.1

172.22.3.4

192.168.55.66

Class Network part Host part CIM 2465 IP Addressing Scheme 9

Network Classes (4)

• IPv4 uses class D IP addresses to multicast packets to a multicast destination IP address (all hosts will receive a copy of the packet) • Table 9-7 • Values of 0 and 127 are not listed in the first octet – 127.0.0.1, loopback IP address – Network 0.0.0.0 has been reserved CIM 2465 IP Addressing Scheme 10

Network Classes (5)

• IP network number (network ID) is a dotted-decimal number that represents a particular IP network. E.g. 10.0.0.0

• First and last number in a network are reserved – 10.0.0.0 (network ID) – 10.255.255.255 (network broadcast address) IP Address 10.1.1.1

172.22.3.4

192.168.55.66

Class Network address Host address CIM 2465 IP Addressing Scheme 11

Network Classes (6)

• Fig 9-17 CIM 2465 IP Addressing Scheme 12

Number of Hosts per Network

• Depends on number of bits of the Host part Class Network part (bits) Host part (bits) Number of Hosts per Network A B C CIM 2465 IP Addressing Scheme 13

Number of Class A, B, C Networks

• Depends on number of bits of the network part • How many class A? 2 8 ? 2 8 – 2 ?

Class Network part (bits) A “Fixed” bits at beginning Bits that can vary Number of Networks B C CIM 2465 IP Addressing Scheme 14

Subnetting (1)

• Subnetting allows the network designer to subdivide a classful IP network into smaller groups, called subnets • Class A network 10.0.0.0, was divided into three subnets – 10.1.1

– 10.1.2

– 10.1.3

CIM 2465 IP Addressing Scheme 15

Subnetting (2)

• Key rules – Devices on the same LAN must use IP addresses in the same group (

IP subnet

) – Devices on different LANs that are separated by at least one router must use IP addresses in different

IP subnet

– IP addresses must be unique inside the same internetwork • Subnet: A group of IP addresses that all have the same value in the first part of the address • Subnet number: A dotted-decimal number that represents a particular IP subnet CIM 2465 IP Addressing Scheme 16

• Three subnets – IP addresses beginning with 10.1.1

– IP addresses beginning with 10.1.2

– IP addresses beginning with 10.1.3

CIM 2465 IP Addressing Scheme 17

Various Views of Subnetted IP Addresses

• Fig 9-19 CIM 2465 IP Addressing Scheme 18

Subnet Mask

• To find out the network (and subnet) parts of an IP address, thus determine whether two hosts are in the same network • To determine if the network is subnetted Subnet Host IP Address 10.1.2.3

Mask 255.0.0.0

172.22.109.4

255.255.0.0

192.168.1.109 255.255.255.0

10.1.2.3

172.22.109.4

255.255.0.0

255.255.224.0

192.168.1.109 255.255.255.224

Class Network CIM 2465 IP Addressing Scheme 19

Ensuring Unique IP Addresses Throughout the Internet

• Unique IP addresses on all computers?

• Unique Network Address for Each Enterprise Network • Internet Assigned Numbers Authority (IANA), IANA member organizations • IPv4 Address Depletion – NAT, Private IP Networks – IPv6 (128 bits) CIM 2465 IP Addressing Scheme 20

• Fig 9-20 CIM 2465 IP Addressing Scheme 21

NAT and Private IP Networks (1)

• NAT allows a company to use just a few registered IP addresses instead of an entire registered Class A, B, or C networks • Fig 9-21 CIM 2465 IP Addressing Scheme 22

NAT and Private IP Networks (2)

Class Range of Network Numbers A 10.0.0.0

Total Number of Networks 1 B 172.16.0.0 – 172.31.0.0

C 192.168.0.0 – 192.168.255.0

CIM 2465 IP Addressing Scheme 16 256 23

IPv4 Vs IPv6

CIM 2465 IP Addressing Scheme 24

Assigning and Mapping IP Addresses

• A planning process • Two popular methods – Static IP Address Configuration – Dynamic configuration using (DHCP) CIM 2465 IP Addressing Scheme 25

Static IP Address Configuration

• Fixed IP addresses entered by users • Key Config Options – IP address, Subnet mask, Default gateway, DNS server • Fig 9-23 CIM 2465 IP Addressing Scheme 26

CIM 2465 IP Addressing Scheme 27

Dynamic IP Config Using DHCP

• Dynamic Host Configuration Protocol (DHCP) • DHCP allows a host that does not have a static IP address configured on an interface to send a request to a DHCP server • The server then sends back a DHCP reply (IP address that can be used, mask, default gateway, and DNS server, and other control information) CIM 2465 IP Addressing Scheme 28

• Fig 9-25 CIM 2465 IP Addressing Scheme 29

• Fig 9-26

DHCP Mechanism

CIM 2465 IP Addressing Scheme 30

Advantages of using DHCP

• When companies move employees and their PCs, the PCs can be installed in the new offices, send a DHCP request, and be up and running • Laptop computers can be moved all over a network (company, home, hotel…) • DHCP server can keep statistics of the usage of IP addresses • DHCP reclaims the IP address once the lease expires so another host can use the IP addresses CIM 2465 IP Addressing Scheme 31

Why use Static IP

• Server IP addresses need to stay the same • Routers, switches need to stay at the same IP addresses • End-user hosts do not move often • Network administration CIM 2465 IP Addressing Scheme 32

Using ARP

• For an IP host to send an IP packet over a LAN, the sending host must know the Ethernet MAC address of another device on the LAN • By Address Resolution Protocol (ARP) CIM 2465 IP Addressing Scheme 33

CIM 2465 IP Addressing Scheme 34

ARP Process

CIM 2465 IP Addressing Scheme 35

Using IP ARP in Larger Network

CIM 2465 IP Addressing Scheme 36

CIM 2465 IP Addressing Scheme 37